Order VIII
HYDROPELTIDEÆ.
This order differs from Nymphæaceæ chiefly in having a definite number of seeds. It consists of only two genera, each containing a single species. Both are little floating plants of tropical and northern America. Nothing is known of their properties. 1240 Hydropéltis H. K.
ORDER IX. NYMPHÆACE.
Like the last, these are all floating plants, and, to gardeners, possessed of great interest, on account of the elegant form and various hues of their flowers Three species are known as the lilies of our own streams and ponds, and the remainder occupy similar stations in other countries. Some of the Indian species of Nymphæ'a are delightfully fragrant. The holy Cyamus, or Pythagorean bean of antiquity, is the produce of the Nelúmbium, a stately aquatic, which abounds in all the hotter countries of the East, where its roots are frequently used as an article of food. The ditches, about Pekin and other Chinese cities, are literally choaked up with its abundance. The pericarpia or beans are oblong, hard, smooth bodies, and possess the power of vegeits abundance. The pericarpia or beans are oblong, hard, smooth bodies, and possess the power of vegetating after having been dried for even thirty years. The flowers and roots of the common white Nymphæ'a have been long celebrated for their sedative and antiaphrodisiacal qualities, which are, however, now considered doubtful. In Sweden, in years of scarcity, the roots of Nuphar lútea are pounded into cakes along with the inner bark of Pinus sylvestris.
NATURAL ARRANGEMENT.
This order has been the cause or much difference among botanists, as to its true station in a natural classification, its structure being of so doubtful a character as to leave room for disputing whether it belongs to Dicotyledones or Monocotyledones. Upon this subject M. Decandolle has the following remarks: "Gærtner declares that the embryo is undivided, and therefore monocotyledonous. In 1802, I remarked in the Bulletin Philomathique, that the embryo both of Nymphæ'a and Núphar is enclosed in a peculiar integument, and that a dicotyledonous structure is apparent when that integument is removed; shortly after, M. Mirbel declared that the embryo of Nelúmbium has two thick cotyledones; in 1806, M. Turpin gave an accurate description of the fruit of Nelúmbium lúteum, without however removing the doubts about the real structure of the embryo, and two years afterwards his colleague, M. Poiteau, described the seed and germination of the same plant, pointing out that the embryo consisted of two thick cotyledons enclosed within a stipular membrane, but destitute of radicula: this was subsequently confirmed by M. Mirbel after very minute anatomical examination; that observer compared the seed of Nelúmbium to the seed of Amygdalus, and also to that of Píper and Saurúrus, and also demonstrated that the structure of the stem was analogous to that of exogenous or dicotyledonous plants. A very different opinion was shortly afterwards held by M. Correa de Serra, an observer of the highest order, who admitted indeed that Nymphæaceæ are exogenous, but contended that the parts which had been taken by previous observers for cotyledons were, in fact, a mere expansion of the radicle, and that cotyledons were as entirely absent in Nelúmbium as in Cúscuta. In the meanwhile M. de Jussieu adhered to the old opinion, that Nymphæaceæ are monocotyledonous; in which he was supported by the late Professor Louis Claude Richard, a name for ever memorable in the annals of Carpology, who published a new view of their structure, in which he differed materially from all his predecessors; this botanist considered the stipulary membrane of Poiteau a simple cotyledon, and the cotyledons of that writer the hypoblastus, or body of the radicula; he also refused to admit any evidence derived from the anatomical structure of the stem. In this conflict of opinions, I have determined to station Nymphæaceæ among Exogenes, for the following reasons: 1st, because the structure of their stem is that of Exogenes rather than of Endogenes; 2dly, because the two opposite bodies, enclosed within the little bag or stipulary membrane, described by Poiteau, appear to be undoubtedly cotyledons, which is confirmed by the presence of a plumula between them in Nelúmbium; 3dly, because of the structure of their flower, which has a great affinity with that of Pæónia, Magnólia, and Papáver; 4thly, on account of the similarity between their fruit and stigma and that of Papaver; 5thly, because of their milky juice and convolute leaves, two characters which are not known to exist among Endogenes." Those who are interested in pursuing this curious discussion any farther, will find many remarks and illustrative figures in the English edition of the Analyse du Fruit, published by Mr. Lindley in 1819. 1174 Nymphæ'a W. 1176 Núphar H. K. 1177 Eurýale H. K.
Section 2. Carpella solitary or connate; Placentæ parietal.